Safety on our nation's roadways is an issue of ever increasing concern. Approximately 40,000 people were killed in automobile accidents during 1992. In an effort to reduce these high fatality numbers, the government has enacted strict automobile crash worthiness requirements. Although these requirements do provide greater safety for passengers involved in an accident, the best way to reduce automobile related injuries is to prevent accidents in the first place.
An effective method of avoiding accidents is the art of defensive driving. Defensive driving is based upon what is known in the driver's education field as the IPDE system. This acronym stands for "identify, predict, decide and execute." A driver must identify potential accident threats, predict how the threat will react, decide the appropriate course of action and execute the decided course.
The controlling factor governing the effectiveness of the IPDE system is the length of time available between the driver's identification of a potential threat and the driver's execution of the proper collision avoidance maneuver. The average reaction time for an alert driver is approximately 3/4 of a second. This means that it takes 3/4 of a second for the driver to identify the danger, predict how the danger will react, decide the appropriate course of action and execute the proper evasive action maneuver. During this 3/4 of a second, the vehicle continues forward at a constant velocity. Therefore, a vehicle traveling at a speed of 65 miles per hour traverses approximately 71.5 feet from the time the driver identifies the danger until the driver executes an evasive action such as applying the brakes. Additionally, it takes the vehicle approximately 380 feet for the brakes to bring the vehicle to a complete stop. Therefore, an average vehicle travels approximately 451 feet from the time a driver identifies a potential danger until the vehicle can come to a complete stop. This stopping distance projected in front of the vehicle in called the vehicle danger zone. If a mobile hazard such as person or animal enters into this danger zone, the vehicle has no means of stopping before impact.
Under normal driving conditions, the driver can identify a potential danger and make the proper evasive maneuver long before the hazard enters into the danger zone. However, certain types of factors can impair the driver's ability to identify hazards. For example, environmental factors such as darkness, fog, rain, snow, glare, etc. can greatly reduce a driver's sight distance. Additionally, certain types of road characteristics such as curves, hills and blind intersections inherently impair visibility. Finally, the reality of human imperfection in the form of fatigue, daydreaming and distractions can substantially reduce a person's reaction time thereby increasing the length of the danger zone projected in front of the vehicle.
When a driver is experiencing a condition of impaired visibility as previously described, it is common for the driver's sight distance to be shorter than the vehicle's danger zone length for the particular speed at which the vehicle is traveling. Under these circumstances, the driver will be unable to identify an unexpected hazard in the roadway until it is too late to avoid an accident. Common types of unexpected mobile hazards include: emergency vehicles racing through intersections; disabled vehicles blocking traffic lanes; approaching trains; and joggers, bicyclists, snowmobilers, cross country skiers and pedestrians using roadways for recreational purposes. Additionally, wild and domestic animals routinely dart into the danger zones of approaching vehicles leaving the driver insufficient time to avoid impact.
Known accident prevention systems alert drivers to posted regulatory conditions of a stationary nature. However, these systems do not forewarn a driver of the presence of mobile hazards which may be a source of danger to the approaching vehicle. Additionally, these systems do not provide a means for alerting individuals and animals that may be in a hazardous location to vacate the path of an approaching vehicle. Several other systems transmit ultrasonic sound waves in front of the vehicle in order to induce animals to vacate the roadway. However, these systems are inaudible to humans. Additionally, certain studies have indicated that ultrasonic sound waves may not be an effective means of inducing animals to vacate the roadway. Trains have long utilizes alternating flashing lights, moving from side to side to prevent animal fixation on the bright lights, but train animal collisions persist.
What is needed is a vehicle accident prevention system that induces animals and people to vacate the path of an approaching vehicle while simultaneously alerting the driver that the vehicle is approaching a potential mobile safety hazard thereby inducing the driver to execute the appropriate evasive action.